Some valves that normally control a gas flow can collect water, e.g., from condensation. In some instances the valve may be immersed in water, e.g., if the valve is closed. If the ambient temperature is cold enough, a valve may become frozen and stuck in place.
One technique to prevent freezing in valves is to locate moveable valve elements above the portion of the valve body where water will first collect. Another technique is to limit contact area in a closed valve between a moveable part and a stationary portion of the valve such that the separation force, in the event the parts become frozen together, is relatively low. However, in the case where the valve body is filled with water, freezing can still cause the valve to become stuck in place.